HP 8569B Spectrum AnalyzerGPIB Software

I've written a program to capture screen images from an HP 8569B spectrum
analyzer (an early-80s analyzer that covers from 10MHz to 22GHz).
This program runs under the Linux operating system using the
LinuxGpib driver and
interface library, and the perl programming language.

The screen capture software generates a PNG format graphics file that more
or less matches what you see on the screen, with a few extra features.
There is currently the ability to mark and annotate the peak signal in the
display; I plan to extend this to allow marking both the max and the min
signals, and display the delta between the two.

You can also choose multiple colors for the trace, and force the output
image to be transparent. Used together, those features mean that you can
use Photoshop or the Gimp to "stack" several traces into a single image.
Here's an example of a stacked trace: